JP2006100932A - Communication system, wireless communication terminal, and base station - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To realize an appropriate communication control in accordance with deterioration causes of a reception state. <P>SOLUTION: A control section of a wireless communication terminal detects a reception state of data in its own terminal (S1). The reception state includes the presence/absence of a packet loss. Then the control section discriminates the presence/absence of the packet loss (S2) and compares a reception amount of a base station for a prescribed period with a reception data amount for a wireless range of its own terminal when any loss exists (S3). Thereafter the control section starts communication control processing corresponding to the deterioration in the detected data reception state on the basis of a received data amount between a server and the base station and the received data amount between the base station and the wireless communication terminal (S4 to S7). <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a communication system, a wireless communication terminal, and a base station.

  In the cellular communication system, one wireless base station performs wireless communication simultaneously with a plurality of wireless communication terminals, and with the recent increase in demand, it is required to increase transmission efficiency. A cdma2000 1xEV-DO method optimized for high-speed packet data is known as a high-speed wireless data communication method that improves the transmission efficiency of a downlink from a wireless base station to a wireless communication terminal.

  The above cdma2000 1xEV-DO system is a standardized version of the HDR (High Data Rate) system, which is an extension of cdma2000 1x by Qualcomm. Std.T-64 1S-2000 CS0024 “cdma2000 High Rate Standardized by the “Packet Data Air Interface Specification”, cdmaOne method currently being serviced by KDDI in Japan (ARIB T-53 in Japan, EIA / TIA / IS-95 etc. in North America, Korea, etc.) However, the cdma2000 1x system corresponding to the third generation system (3G) is a system aimed at further improving the communication speed by specializing in data communication. In cdma2000 lxEV-DO, EV means Evolution and DO means Data only.

  In the cdma2000 1xEV-DO method, when the reception state of the terminal is good by switching the modulation method of data transmitted from the wireless base station to the terminal based on the information notified of the reception state received from the mobile communication terminal Has a low error tolerance but a high communication rate, and a low communication error rate but a high error tolerance can be used when reception is bad.

  In the cdma2000 1xEV-DO downlink direction (the direction from the radio base station to the mobile communication terminal), the time is divided in units of 1/600 second, and only one mobile communication terminal is communicated within that time. In addition, time division multiplex access (TDMA) is employed in which communication is performed with a plurality of portable communication terminals by switching the communication partner portable communication terminal according to time. As a result, the radio base station can always transmit data with the maximum power to each mobile communication terminal, and can perform data communication between mobile communication terminals at the fastest communication speed. (See, for example, Patent Document 1).

  In the cdma2000 1xEV-DO wireless communication system described above, a wireless communication terminal uses wireless packet communication to access a distribution server connected to an Internet (IP) network such as the Internet and receive streaming data such as moving image data. And playback is realized. In this streaming data distribution system, a distribution server packetizes streaming data in response to a distribution request from a wireless communication terminal and transmits the packet to the wireless communication terminal. The transmitted packet is transferred to the packet network (wireless packet network) by the wireless communication system via the IP network, and transferred to the wireless base station connected to the destination wireless communication terminal. The wireless base station wirelessly transmits the received packet to the destination wireless communication terminal according to the wireless communication protocol. The wireless communication terminal verifies the data of the wirelessly received packet, and if there is no problem, reproduces the streaming data.

  In the wireless section between the wireless base station and the wireless communication terminal, transmission data may be erroneous due to deterioration of the wireless environment such as the radio wave condition. The wireless communication terminal requests retransmission to the wireless base station when there is an error in the data of the received packet or for a packet that could not be received within a predetermined time. Upon receiving the retransmission request, the radio base station transmits the corresponding packet held for retransmission to the retransmission request source radio base station. As a result, the retransmission process is executed only in the wireless section, and the packet loss occurring in the wireless section is reduced.

  However, the above-described retransmission processing in the wireless section causes a large delay and jitter in reproducing streaming data. For this reason, conventionally, a time limit value for resending processing is set, and when the resending processing time exceeds the time limit value, the packet to be resent is discarded and resending is stopped and transmitted to the next packet of the data stream. A technique (prior art 1) for switching objects is known.

Also, the transmission speed on the IP network varies according to the amount of traffic that changes from moment to moment, but if the transmission speed on the IP network is slower than the transmission speed of the packet transmitted by the distribution server, Loss will occur. For this reason, a technique (prior art 2) is known in which the transmission speed of the distribution server is dynamically changed in accordance with the reception status such as the data loss rate and data delay time obtained at the receiving terminal.
JP 2002-300634 A

  However, in the above-described prior art 1, when the cause of the packet loss is congestion in the IP network, even if the packet retransmission processing in the wireless section is stopped, the packet loss eventually occurs on the IP network. The re-sending process of the radio section due to the loss is started. As a result, the packet retransmission process due to the packet loss on the IP network and the cancellation of the retransmission process are repeated, which causes a problem that the reproduction of streaming data is not normally performed.

  This problem also occurs when packet loss occurs due to congestion in the wireless packet network. As described above, in the downlink direction of the cdma2000 1xEV-DO method, one radio base station communicates wirelessly with a plurality of mobile communication terminals by time division multiple access, so communication per terminal according to the number of simultaneously connected terminals. The speed fluctuates. Thereby, when the communication speed of the mobile communication terminal becomes less than the transmission speed of the streaming data from the distribution server, packets that cannot be transmitted to the mobile communication terminal are accumulated in the buffer in the radio base station. When this amount of storage increases, the mobile communication terminal does not receive a packet within a predetermined time, so that it is detected as a packet loss and a retransmission is requested to the radio base station. Even in this case, even if the retransmission processing is canceled by the prior art 1 and the packet buffered in the radio base station is discarded, the packet that cannot be transmitted to the mobile communication terminal is not transmitted to the mobile communication terminal unless congestion in the radio packet network is resolved. Since buffering is performed in the station, packet retransmission processing and cancellation of the retransmission processing are repeated.

  Further, in the above-described conventional technique 2, control is performed to reduce the transmission speed of the distribution server even in the case of a reception error (such as packet loss due to a transmission error in the wireless section) unique to the wireless communication system described above. End up. As a result, the transmission speed of the distribution server is reduced during packet retransmission in the wireless section, but this does not contribute to eliminating the delay in reproduction of streaming data, and streaming that requires real-time performance. Not suitable for applications.

  The present invention has been made in consideration of such circumstances, and an object of the present invention is to provide a communication system, a wireless communication terminal, and a base station that can perform appropriate communication control in accordance with a deterioration factor of reception conditions. There is.

  In order to solve the above problems, a communication system according to the present invention relates to a first monitoring unit that monitors a received data amount between a server and a base station, and a received data amount obtained by the first monitoring unit. A base station having notification means for notifying information to a wireless communication terminal; a receiving means for receiving information related to the received data amount; and a second receiving means for monitoring a received data amount between the base station and the wireless communication terminal. Monitoring means, control means for controlling communication between the base station and the wireless communication terminal based on information on the received data amount based on the second monitoring means and information on the received received data amount; , And a wireless communication terminal.

  In the communication system according to the present invention, the wireless communication terminal has a detection unit that detects a packet loss of data transmitted from the base station, and the control unit detects the packet loss when the detection unit detects a packet loss. And controlling communication between the base station and the wireless communication terminal based on the information on the received data amount based on the second monitoring means and the information on the received received data amount. .

  In the communication system according to the present invention, when the received data amount between the base station and the wireless communication terminal is smaller than the received data amount between the server and the base station, the control means The retransmission control is not performed.

  The base station according to the present invention comprises monitoring means for monitoring the amount of received data between the server and the base station, and notification means for notifying the wireless communication terminal of information relating to the amount of received data obtained by the monitoring means. It is characterized by that.

  A wireless communication terminal according to the present invention includes a receiving unit that receives information on a received data amount between a server and a base station from a base station, and a monitor that monitors the received data amount between the base station and the wireless communication terminal. And control means for controlling communication between the base station and the radio communication terminal based on information on the received data amount based on the monitoring means and information on the received received data amount. It is characterized by.

  The communication system according to the present invention notifies the wireless communication terminal of the first monitoring means for monitoring the amount of received data between the server and the base station, and information related to the received data amount obtained by the first monitoring means. A base station having a notification means, a receiving means for receiving information relating to the received data amount, a second monitoring means for monitoring a received data amount between the base station and a wireless communication terminal, and the second monitoring And a control means for instructing the server to change the transmission rate based on the information on the received data amount based on the means and the information on the received received data amount. And

  In the communication system according to the present invention, the wireless communication terminal has a detection unit that detects a packet loss of data transmitted from the base station, and the control unit detects the packet loss when the detection unit detects a packet loss. In addition, a transmission rate change instruction is issued to the server based on information on the received data amount based on the second monitoring means and information on the received received data amount.

  In the communication system according to the present invention, when the amount of received data between the base station and the wireless communication terminal is larger than the amount of received data between the server and the base station, the control means transmits a transmission rate to the server. It is characterized by issuing a change instruction to increase

  The base station according to the present invention includes a monitoring unit that monitors a received data amount between the server and the base station, a notification unit that notifies a wireless communication terminal of information related to the received data amount obtained by the monitoring unit, Transmission means for transmitting to the server a transmission rate change instruction for the server received from a wireless communication terminal.

  A wireless communication terminal according to the present invention includes a receiving unit that receives information on a received data amount between a server and a base station from a base station, and a monitor that monitors the received data amount between the base station and the wireless communication terminal. And a control means for instructing the server to change the transmission rate based on the information related to the received data amount based on the monitoring means and the information related to the received received data amount.

  ADVANTAGE OF THE INVENTION According to this invention, appropriate communication control by discrimination | determination of the reception condition degradation factor based on each received data amount of the base station side and the radio | wireless communication terminal side can be performed. As a result, distribution control of streaming data according to the state of the IP network or the wireless packet network can be performed, and the reproduction quality of the streaming data can be improved.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 is a block diagram showing a configuration of a communication system according to an embodiment of the present invention. In FIG. 1, a wireless communication terminal 1 according to an embodiment of the present invention is a cdma2000 1xEV-DO wireless communication terminal, for example, a mobile phone. The wireless communication terminal according to the present invention is not limited to a portable type. The radio base station 2 is a cdma2000 1xEV-DO base station. The wireless communication terminal 1 is wirelessly connected to the wireless base station 2 and performs voice communication (for example, VoIP) or data communication.

  The wireless base station 2 transmits and receives packets to and from the IP network 3 such as the Internet via a wireless packet network (not shown). The wireless communication terminal 1 can be connected to the IP network 3 via the wireless base station 2.

  The distribution server 4 is connected to the IP network 3 and packetizes streaming data such as moving image data and distributes the packetized data to the distribution requesting terminal via the IP network 3.

  In FIG. 1, the wireless communication terminal 1 accesses the distribution server 4 connected to the IP network 3 by wireless packet communication and requests streaming data such as moving image data. The distribution server 4 packetizes the streaming data in response to a distribution request from the wireless communication terminal 1 and transmits it to the wireless communication terminal 1. The transmitted packet is transferred to the wireless base station 2 connected to the destination wireless communication terminal 1 via the IP network 3. The radio base station 2 transmits the received packet to the destination radio communication terminal 1 via a radio line according to the radio communication protocol. The wireless communication terminal 1 verifies the data of the packet received via the wireless line, and if there is no problem, reproduces the streaming data.

  FIG. 2 is a block diagram showing a configuration of the wireless communication terminal 1 shown in FIG. In FIG. 2, the control unit 11 includes a CPU, a memory, and the like, and controls each unit of the wireless communication terminal 1. The operation unit 12 includes a numeric keypad for inputting a telephone number and the like, various function keys, and the like, and outputs input data to the control unit 11. The display unit 13 includes a display panel such as a liquid crystal display panel and a display control circuit. The display unit 13 receives display data from the control unit 11 and controls display.

  The radio unit 14 transmits and receives radio signals to and from the radio base station 2 via an antenna, and performs voice communication or data communication. The voice control unit 15 processes voice transmitted / received via the wireless unit 14. The microphone 16 inputs sound to the sound control unit 15 under the control of the control unit 11. The speaker 17 outputs a call voice processed by the voice control unit 15 under the control of the control unit 11. The storage unit 18 stores various data used by the control unit 11. The streaming data distributed from the distribution server 4 is stored in the storage unit 24 and is read from the storage unit 24 during reproduction. The received data amount monitoring unit 19 monitors the received data amount based on the received packet received from the radio base station 2. The monitoring data is notified to the control unit 11.

  FIG. 3 is a block diagram showing a configuration of the radio base station 2 shown in FIG. In FIG. 3, the control unit 21 includes a CPU, a memory, and the like, and controls each unit of the radio base station 2. The wireless unit 22 transmits and receives wireless signals to and from the wireless communication terminal 1 via an antenna, and transmits and receives data related to voice communication or data communication by the wireless communication terminal 1. The communication unit 23 connects to the IP network 3 and transmits / receives packets. For example, a packet from the distribution server 4 in FIG. 1 is received, and a packet from the wireless communication terminal 1 is transmitted to the IP network 3.

  The storage unit 24 stores various data used by the control unit 21. The storage unit 24 is provided with a buffer for accumulating packets that cannot be transmitted to the wireless communication terminal 1. In addition, a buffer for holding a packet for retransmission is provided. The received data amount monitoring unit 25 monitors the received data amount for each wireless communication terminal 1 based on the received packet received from the distribution server 4 via the IP network 3. The monitoring data is notified to the control unit 21.

Next, in the communication system shown in FIG. 1, an operation when streaming data is packetized and distributed from the distribution server 4 to the wireless communication terminal 1 will be described.
FIG. 4 is a flowchart showing a flow of data communication control processing by the control unit 11 of the wireless communication terminal 1 shown in FIG.

  The wireless communication terminal 1 periodically receives the received data amount information of the base station from the connected wireless base station 2. This received data amount information indicates the amount of data received by the wireless base station 2 addressed to the wireless base station 2 based on the received packet received from the distribution server 4 via the IP network 3 within a predetermined period. Information. Based on the received data amount information received from the wireless base station 2, the control unit 11 of the wireless communication terminal 1 calculates transition data of the received data amount at the base station. For example, the data reception speed for a certain period is calculated. In addition, the control unit 11 of the wireless communication terminal 1 receives data in the wireless section of the terminal for a certain period based on the received data amount of the terminal transmitted from the wireless base station 2 obtained from the received data amount monitoring unit 19. The transition data of the data amount is calculated similarly.

  The control unit 11 of the wireless communication terminal 1 activates the process of FIG. 4 at a constant cycle. In FIG. 4, the control unit 11 detects the reception status at the terminal itself (step S1). This reception status includes the presence or absence of packet loss. Next, the control unit 11 determines whether or not there is a packet loss (step S2). If the result of this determination is that there is a packet loss (YES in step S2), the control unit 11 compares the received data amount at the base station described above for a predetermined period with the received data amount in the radio section of the terminal itself ( Note that transition data may be used) (step S3). As a result of this comparison, if the received data amount (or transition) is larger in the wireless section than in the section between the base station and the distribution server 4 (YES in step S4), the received packet is stagnated in the base station. Therefore, it can be determined that the received packet from the distribution server 4 is smoothly transferred to the wireless communication terminal 1. That is, it can be determined that the packet loss occurs in the middle of the route of the IP network 3. Accordingly, the control unit 11 requests the distribution server 4 to reduce the packet transmission rate (step S5). In response to this request, the distribution server 4 performs packet transmission at a reduced transmission speed. As a result, if the transmission speed from the distribution server 4 is kept below the transmission speed on the IP network 3, the packet arrives at the wireless communication terminal 1 without loss, and the streaming data is normally played back. It becomes like this.

  On the other hand, as a result of the comparison in step S3, if the received data amount (or transition) in the wireless section is less than the received data amount (or transition) in the section between the base station and the distribution server 4 (NO in step S4). It can be determined that the received packet is stagnated at the base station and the received packet from the distribution server 4 is not smoothly transferred to the wireless communication terminal 1. In this case, the control unit 11 determines whether or not there is a retransmission request in the wireless section in step S6 (step S6). If the result of this determination is that there is a retransmission request (YES in step S6), it can be determined that the received packet has stagnated in the base station as a result of retransmission in the radio section. Thereby, the control part 11 stops resending of a radio area (step S7). In response to this retransmission stop request, the radio base station 2 cancels the retransmission and discards the received packet held for retransmission.

  As a result of the determination in step S6, if there is no retransmission request (NO in step S6), it can be determined that the received packet is delayed in the base station as a result of congestion in the wireless section. That is, since the number of terminals connected to the same base station is large and the communication speed per terminal is insufficient, the received packet from the distribution server is not smoothly transferred from the base station to the wireless communication terminal 1. I can judge. Accordingly, the control unit 11 requests the distribution server 4 to reduce the packet transmission rate (step S5). In response to this request, the distribution server 4 performs packet transmission at a lower transmission rate. As a result, if the transmission rate from the distribution server 4 is kept below the transmission rate of the wireless section, the packet is lost without stagnation in the base station. Thus, the mobile station arrives at the wireless communication terminal 1 and the streaming data is normally played back.

  If it is determined in step S2 that there is no packet loss (NO in step S2), the control unit 11 considers the reproduction status of the streaming data and transmits a packet to the distribution server 4 as necessary. A request is made to increase the speed (step S8). In response to this request, the distribution server 4 increases the transmission speed and performs packet transmission. Thereby, for example, the wireless communication terminal 1 can receive high-quality video streaming.

  As described above, according to the present embodiment, it is possible to perform appropriate communication control by determining the reception status deterioration factor based on the received data amounts on the radio base station side and the radio communication terminal side. As a result, distribution control of streaming data according to the state of the IP network or the wireless packet network can be performed, and the real-time property and reproduction quality of the streaming data can be improved.

  The embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration is not limited to this embodiment, and includes design changes and the like within a scope not departing from the gist of the present invention.

It is a block diagram which shows the structure of the communication system which concerns on one Embodiment of this invention. It is a block diagram which shows the structure of the radio | wireless communication terminal 1 shown in FIG. It is a block diagram which shows the structure of the wireless base station 2 shown in FIG. 3 is a flowchart showing a flow of data communication control processing by a control unit 11 of the wireless communication terminal 1 shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Wireless communication terminal, 2 ... Wireless base station, 3 ... IP network, 4 ... Distribution server, 11, 21 ... Control part, 12 ... Operation part, 13 ... Display part, 14, 22 ... Wireless part, 15 ... Voice control , 16 ... microphone, 17 ... speaker, 18, 24 ... storage unit, 19, 25 ... received data amount monitoring unit, 23 ... communication unit.

Claims (10)

A base station comprising: first monitoring means for monitoring the amount of received data between the server and the base station; and notification means for notifying the wireless communication terminal of information relating to the amount of received data obtained by the first monitoring means; ,
Receiving means for receiving information relating to the received data amount, second monitoring means for monitoring the received data amount between the base station and the wireless communication terminal, information relating to the received data amount based on the second monitoring means, A wireless communication terminal having control means for controlling communication between the base station and the wireless communication terminal based on the received information regarding the received data amount;
A communication system comprising: The wireless communication terminal has detection means for detecting a packet loss of data transmitted from the base station,
When the detection unit detects a packet loss, the control unit performs wireless communication with the base station based on information on the received data amount based on the second monitoring unit and information on the received received data amount. The communication system according to claim 1, wherein communication with a terminal is controlled.   The control means does not perform retransmission control with the base station when the amount of received data between the base station and the wireless communication terminal is smaller than the amount of received data between the server and the base station. The communication system according to claim 1. Monitoring means for monitoring the amount of received data between the server and the base station;
Notification means for notifying the wireless communication terminal of information relating to the amount of received data obtained by the monitoring means;
A base station comprising: Receiving means for receiving information on the amount of received data between the server and the base station from the base station;
Monitoring means for monitoring the amount of received data between the base station and the wireless communication terminal;
Control means for controlling communication between the base station and the wireless communication terminal based on information on the received data amount based on the monitoring means and information on the received received data amount;
A wireless communication terminal comprising: A base station comprising: first monitoring means for monitoring the amount of received data between the server and the base station; and notification means for notifying the wireless communication terminal of information relating to the received data amount obtained by the first monitoring means. When,
Receiving means for receiving information on the amount of received data, second monitoring means for monitoring the amount of received data between the base station and the wireless communication terminal, information on the amount of received data based on the second monitoring means, A wireless communication terminal having control means for instructing the server to change a transmission rate based on the received information on the received data amount;
A communication system comprising: The wireless communication terminal has detection means for detecting a packet loss of data transmitted from the base station,
When the detection unit detects a packet loss, the control unit transmits a transmission rate to the server based on the information on the received data amount based on the second monitoring unit and the information on the received received data amount. The communication system according to claim 6, wherein a change instruction is issued.   When the amount of received data between the base station and the wireless communication terminal is larger than the amount of received data between the server and the base station, the control means instructs the server to change the transmission rate. The communication system according to claim 6. Monitoring means for monitoring the amount of received data between the server and the base station;
Notification means for notifying the wireless communication terminal of information relating to the amount of received data obtained by the monitoring means;
A transmission means for transmitting a transmission rate change instruction for the server received from the wireless communication terminal to the server;
A base station comprising: Receiving means for receiving information on the amount of received data between the server and the base station from the base station;
Monitoring means for monitoring the amount of received data between the base station and the wireless communication terminal;
Control means for instructing the server to change the transmission rate based on information on the received data amount based on the monitoring means and information on the received received data amount;
A wireless communication terminal comprising:

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